Effect of alkyl chain lengths on the assemblies of magnetic nanoparticles coated with multi-functional thiolactone-containing copolymer

Abstract

This work presents the synthesis of magnetite nanoparticle (MNP) coated with poly(N,N-diethylaminoethyl methacrylate)-b-poly(N-isopropyl acrylamide-st-thiolactone acrylamide) (PDEAEMA-b-P(NIPAAm-st-TlaAm) copolymer and its use in controlled drug release and bio-conjugation. TlaAm units in the copolymer were ring-opened with various alkyl amines to form thiol groups (-SH), followed by thiol-ene coupling reactions with acrylamide-coated MNP and then quaternized to obtain cationic copolymer-MNP assemblies (the size < 200 nm/cluster). The use of alkyl amines having various chain lengths (e.g., 1-propylamine, 1-octylamine, or 1-dodecylamine) in the nucleophilic ring-opening reactions of the thiolactone rings affected their magnetic separation ability, water dispersibility, and release rate of doxorubicin model drug. In all cases, when increasing the temperature, they showed a thermo-responsive behavior as indicated by the decrease in hydrodynamic size and the accelerated drug release rate. These copolymer-MNP assemblies could be used as a novel platform with thermal-triggering controlled drug release and capability for adsorption with any negatively charged biomolecules.

Notes

Acknowledgements

The authors acknowledge the Thailand Research Fund (TRF)(RSA5980002) for financial support. MR thanks the National Research Council of Thailand (NRCT) (R2561B086) for the supports. SP thanks The Royal Golden Jubilee PhD Program (PhD/0210/2556) for the scholarship.

Funding

This study was funded by The Thailand Research Fund (TRF) (RSA5980002), the National Research Council of Thailand (NRCT) (R2561B086), and the Royal Golden Jubilee PhD Program (PhD/0210/2556).